/*
silverPDF is sponsored by Aleyant Systems (http://www.aleyant.com)

silverPDF is based on PdfSharp (http://www.pdfsharp.net) and iTextSharp (http://itextsharp.sourceforge.net)

Developers: Ai_boy (aka Oleksii Okhrymenko)

Permission is hereby granted, free of charge, to any person
obtaining a copy of this software and associated documentation
files (the "Software"), to deal in the Software without
restriction, including without limitation the rights to use,
copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following
conditions:

The above information and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR SPONSORS
BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.

*/
#region PDFsharp - A .NET library for processing PDF
//
// Authors:
//   Stefan Lange (mailto:Stefan.Lange@pdfsharp.com)
//
// Copyright (c) 2005-2008 empira Software GmbH, Cologne (Germany)
//
// http://www.pdfsharp.com
// http://sourceforge.net/projects/pdfsharp
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
// DEALINGS IN THE SOFTWARE.
#endregion

using System;
using System.Diagnostics;
using System.Collections;
using System.Text;
using System.IO;
using PdfSharp.Internal;
using PdfSharp.Pdf.IO;
using PdfSharp.Pdf;
using PdfSharp.Pdf.Advanced;
using PdfSharp.Pdf.Annotations;
using System.Collections.Generic;

namespace PdfSharp.Pdf
{
  /// <summary>
  /// Represents the pages of the document.
  /// </summary>
  [DebuggerDisplay("(PageCount={Count})")]
  public sealed class PdfPages : PdfDictionary, IEnumerable
  {
    internal PdfPages(PdfDocument document)
      : base(document)
    {
      Elements.SetName(Keys.Type, "/Pages");
      Elements[Keys.Count] = new PdfInteger(0);
    }

    public PdfPages(PdfDictionary dictionary)
      : base(dictionary)
    {
    }

    /// <summary>
    /// Gets the number of pages.
    /// </summary>
    public int Count
    {
      get { return this.PagesArray.Elements.Count; }
    }

    /// <summary>
    /// Gets the page with the specified index.
    /// </summary>
    public PdfPage this[int index]
    {
      get
      {
        if (index < 0 || index >= Count)
          throw new ArgumentOutOfRangeException("index", PSSR.PageIndexOutOfRange);

        PdfDictionary dict = (PdfDictionary)((PdfReference)PagesArray.Elements[index]).Value;
        if (!(dict is PdfPage))
          dict = new PdfPage(dict);
        return (PdfPage)dict;
      }
      //set
      //{
      //  if (index < 0 || index >= this.pages.Count)
      //    throw new ArgumentOutOfRangeException("index", index, PSSR.PageIndexOutOfRange);
      //  this.pages[index] = value;
      //}
    }

    /// <summary>
    /// Creates a new PdfPage, adds it to this document, and retruns it.
    /// </summary>
    public PdfPage Add()
    {
      PdfPage page = new PdfPage();
      Insert(Count, page);
      return page;
    }

    /// <summary>
    /// Adds the specified PdfPage to this document and retruns a may be new PdfPage object.
    /// The value returned is a new object if the added page comes from a foreign document.
    /// </summary>
    public PdfPage Add(PdfPage page)
    {
      return Insert(Count, page);
    }

    /// <summary>
    /// Creates a new PdfPage, inserts it at the specified position to this document, and retruns it.
    /// </summary>
    public PdfPage Insert(int index)
    {
      PdfPage page = new PdfPage();
      Insert(index, page);
      return page;
    }

    /// <summary>
    /// Inserts the specified PdfPage at the specified position to this document and retruns a may be new PdfPage object.
    /// The value returned is a new object if the inserted page comes from a foreign document.
    /// </summary>
    public PdfPage Insert(int index, PdfPage page)
    {
      if (page == null)
        throw new ArgumentNullException("page");

      // Is the page already owned by this document
      if (page.Owner == this.Owner)
      {
        // Case: Page is removed and than inserted a another position.
        int count = Count;
        for (int idx = 0; idx < count; idx++)
        {
          if (Object.ReferenceEquals(this[idx], page))
            throw new InvalidOperationException(PSSR.MultiplePageInsert);
        }
        // TODO: check this case
        Owner.irefTable.Add(page);
        PagesArray.Elements.Insert(index, page.Reference);
        Elements.SetInteger(PdfPages.Keys.Count, PagesArray.Elements.Count);
        return page;
      }

      // All page insertions come here
      if (page.Owner == null)
      {
        // Case: New page was created and inserted now.
        page.Document = this.Owner;

        Owner.irefTable.Add(page);
        PagesArray.Elements.Insert(index, page.Reference);
        Elements.SetInteger(PdfPages.Keys.Count, PagesArray.Elements.Count);
      }
      else
      {
        // Case: Page is from an external document -> import it.
        page = ImportExternalPage(page);
        Owner.irefTable.Add(page);
        PagesArray.Elements.Insert(index, page.Reference);
        Elements.SetInteger(PdfPages.Keys.Count, PagesArray.Elements.Count);
        PdfAnnotations.FixImportedAnnotation(page);
      }
      if (Owner.Settings.TrimMargins.AreSet)
        page.TrimMargins = Owner.Settings.TrimMargins;
      return page;
    }

    /// <summary>
    /// Removes the specified page from the document.
    /// </summary>
    public void Remove(PdfPage page)
    {
      PagesArray.Elements.Remove(page.Reference);
      Elements.SetInteger(PdfPages.Keys.Count, PagesArray.Elements.Count);
    }

    /// <summary>
    /// Removes the specified page from the document.
    /// </summary>
    public void RemoveAt(int index)
    {
      PagesArray.Elements.RemoveAt(index);
      Elements.SetInteger(PdfPages.Keys.Count, PagesArray.Elements.Count);
    }

    /// <summary>
    /// Moves a page within the page sequence.
    /// </summary>
    /// <param name="oldIndex">The page index before this operation.</param>
    /// <param name="newIndex">The page index after this operation.</param>
    public void MovePage(int oldIndex, int newIndex)
    {
      if (oldIndex < 0 || oldIndex >= Count)
        throw new ArgumentOutOfRangeException("oldIndex");
      if (newIndex < 0 || newIndex >= Count)
        throw new ArgumentOutOfRangeException("newIndex");
      if (oldIndex == newIndex)
        return;

      PdfPage page = (PdfPage)pagesArray.Elements[oldIndex];
      pagesArray.Elements.RemoveAt(oldIndex);
      pagesArray.Elements.Insert(newIndex, page);
    }

    /// <summary>
    /// Imports an external page. The elements of the imported page are cloned and added to this document.
    /// Important: In contrast to PdfFormXObject adding an external page always make a deep copy
    /// of their transitive closure. Any reuse of already imported objects is not intended because
    /// any modification of an imported page must not change another page.
    /// </summary>
    PdfPage ImportExternalPage(PdfPage importPage)
    {
      if (importPage.Owner.openMode != PdfDocumentOpenMode.Import)
        throw new InvalidOperationException("A PDF document must be opened with PdfDocumentOpenMode.Import to import pages from it.");

      PdfPage page = new PdfPage(this.document);

      CloneElement(page, importPage, PdfPage.Keys.Resources, false);
      CloneElement(page, importPage, PdfPage.Keys.Contents, false);
      CloneElement(page, importPage, PdfPage.Keys.MediaBox, true);
      CloneElement(page, importPage, PdfPage.Keys.CropBox, true);
      CloneElement(page, importPage, PdfPage.Keys.Rotate, true);
      CloneElement(page, importPage, PdfPage.Keys.BleedBox, true);
      CloneElement(page, importPage, PdfPage.Keys.TrimBox, true);
      CloneElement(page, importPage, PdfPage.Keys.ArtBox, true);
#if true
      // Do not deep copy annotations.
      CloneElement(page, importPage, PdfPage.Keys.Annots, false);
#else
      // Deep copy annotations.
      CloneElement(page, importPage, PdfPage.Keys.Annots, true);
#endif
      // TODO more elements?
      return page;
    }

    /// <summary>
    /// Helper function for ImportExternalPage.
    /// </summary>
    void CloneElement(PdfPage page, PdfPage importPage, string key, bool deepcopy)
    {
      Debug.Assert(page.Owner == this.document);
      Debug.Assert(importPage.Owner != null);
      Debug.Assert(importPage.Owner != this.document);

      PdfItem item = importPage.Elements[key];
      if (item != null)
      {
        PdfImportedObjectTable importedObjectTable = null;
        if (!deepcopy)
          importedObjectTable = Owner.FormTable.GetImportedObjectTable(importPage);

        // The item can be indirect. If so, replace it by its value.
        if (item is PdfReference)
          item = ((PdfReference)item).Value;
        if (item is PdfObject)
        {
          PdfObject root = (PdfObject)item;
          if (deepcopy)
          {
            Debug.Assert(root.Owner != null, "See 'else' case for details");
            root = PdfObject.DeepCopyClosure(this.document, root);
          }
          else
          {
            // The owner can be null if the item is not a reference
            if (root.Owner == null)
              root.Document = importPage.Owner;
            root = PdfObject.ImportClosure(importedObjectTable, page.Owner, root);
          }

          if (root.Reference == null)
            page.Elements[key] = root;
          else
            page.Elements[key] = root.Reference;
        }
        else
        {
          // Simple items are just cloned.
          page.Elements[key] = item.Clone();
        }
      }
    }

    /// <summary>
    /// Gets a PdfArray containing all pages of this document. The array must not be modified.
    /// </summary>
    public PdfArray PagesArray
    {
      get
      {
        if (this.pagesArray == null)
          this.pagesArray = (PdfArray)Elements.GetValue(Keys.Kids, VCF.Create);
        return this.pagesArray;
      }
    }
    PdfArray pagesArray;

    /// <summary>
    /// Replaces the page tree by a flat array of indirect references to the the pages objects.
    /// </summary>
    internal void FlattenPageTree()
    {
      // Acrobat creates a balanced tree if the number of pages is rougly more than ten. This is
      // not difficult but obviously also not neccessary. I created a document with 50000 pages with
      // PDF4NET and Acrobat opened it in less than 2 seconds.

      //PdfReference xrefRoot = this.Document.Catalog.Elements[PdfCatalog.Keys.Pages] as PdfReference;
      //PdfDictionary[] pages = GetKids(xrefRoot, null);

      // Promote inheritable values down the page tree
      PdfPage.InheritedValues values = new PdfPage.InheritedValues();
      PdfPage.InheritValues(this, ref values);
      PdfDictionary[] pages = GetKids(this.Reference, values, null);

      // Replace /Pages in catalog by this object
      // xrefRoot.Value = this;

      PdfArray array = new PdfArray(this.Owner);
      foreach (PdfDictionary page in pages)
      {
        // Fix the parent
        page.Elements[PdfPage.Keys.Parent] = this.Reference;
        array.Elements.Add(page.Reference);
      }

      Elements.SetName(Keys.Type, "/Pages");
#if true
      // direct array
      Elements.SetValue(Keys.Kids, array);
#else
      // incdirect array
      this.Document.xrefTable.Add(array);
      Elements.SetValue(Keys.Kids, array.XRef);
#endif
      Elements.SetInteger(Keys.Count, array.Elements.Count);
    }

    /// <summary>
    /// Recursively converts the page tree into a flat array.
    /// </summary>
    PdfDictionary[] GetKids(PdfReference iref, PdfPage.InheritedValues values, PdfDictionary parent)
    {
      // TODO: inherit inheritable keys...
      PdfDictionary kid = (PdfDictionary)iref.Value;

      if (kid.Elements.GetName(Keys.Type) == "/Page")
      {
        PdfPage.InheritValues(kid, values);
        return new PdfDictionary[] { kid };
      }
      else
      {
        Debug.Assert(kid.Elements.GetName(Keys.Type) == "/Pages");
        PdfPage.InheritValues(kid, ref values);
        ArrayList list = new ArrayList();
        PdfArray kids = kid.Elements["/Kids"] as PdfArray;
        //newTHHO 15.10.2007 begin
        if (kids == null)
        {
          PdfReference xref3 = kid.Elements["/Kids"] as PdfReference;
          kids = xref3.Value as PdfArray;
        }
        //newTHHO 15.10.2007 end
        foreach (PdfReference xref2 in kids)
          list.AddRange(GetKids(xref2, values, kid));
        int count = list.Count;
        Debug.Assert(count == kid.Elements.GetInteger("/Count"));
        return (PdfDictionary[])list.ToArray(typeof(PdfDictionary));
      }
    }

    /// <summary>
    /// TODO: Create the page tree.
    /// </summary>
    internal override void PrepareForSave()
    {
      // TODO: Close all open content streams

      // TODO: Create the page tree.
      // Arrays have a limit of 8192 entries, but I successfully tested documents
      // with 50000 pages and no page tree.
      // ==> wait for bug report.
      int count = this.pagesArray.Elements.Count;
      for (int idx = 0; idx < count; idx++)
      {

        PdfPage page = this[idx];
        page.PrepareForSave();
      }
    }

    /// <summary>
    /// Gets the enumerator.
    /// </summary>
    public new IEnumerator GetEnumerator()
    {
      return new PdfPagesEnumerator(this);
    }

    private class PdfPagesEnumerator : IEnumerator
    {
      private PdfPage currentElement;
      private int index;
      private PdfPages list;

      internal PdfPagesEnumerator(PdfPages list)
      {
        this.list = list;
        this.index = -1;
      }

      public bool MoveNext()
      {
        if (this.index < this.list.Count - 1)
        {
          this.index++;
          this.currentElement = this.list[this.index];
          return true;
        }
        this.index = this.list.Count;
        return false;
      }

      public void Reset()
      {
        this.currentElement = null;
        this.index = -1;
      }

      object IEnumerator.Current
      {
        get { return this.Current; }
      }

      public PdfPage Current
      {
        get
        {
          if (this.index == -1 || this.index >= this.list.Count)
            throw new InvalidOperationException(PSSR.ListEnumCurrentOutOfRange);
          return this.currentElement;
        }
      }
    }

    /// <summary>
    /// Predefined keys of this dictionary.
    /// </summary>
    internal sealed class Keys : PdfPage.InheritablePageKeys
    {
      /// <summary>
      /// (Required) The type of PDF object that this dictionary describes; 
      /// must be Pages for a page tree node.
      /// </summary>
      [KeyInfo(KeyType.Name | KeyType.Required, FixedValue = "Pages")]
      public const string Type = "/Type";

      /// <summary>
      /// (Required except in root node; must be an indirect reference)
      /// The page tree node that is the immediate parent of this one.
      /// </summary>
      [KeyInfo(KeyType.Dictionary | KeyType.Required)]
      public const string Parent = "/Parent";

      /// <summary>
      /// (Required) An array of indirect references to the immediate children of this node.
      /// The children may be page objects or other page tree nodes.
      /// </summary>
      [KeyInfo(KeyType.Array | KeyType.Required)]
      public const string Kids = "/Kids";

      /// <summary>
      /// (Required) The number of leaf nodes (page objects) that are descendants of this node 
      /// within the page tree.
      /// </summary>
      [KeyInfo(KeyType.Integer | KeyType.Required)]
      public const string Count = "/Count";

      /// <summary>
      /// Gets the KeysMeta for these keys.
      /// </summary>
      public static DictionaryMeta Meta
      {
        get
        {
          if (Keys.meta == null)
            Keys.meta = CreateMeta(typeof(Keys));
          return Keys.meta;
        }
      }
      static DictionaryMeta meta;
    }

    /// <summary>
    /// Gets the KeysMeta of this dictionary type.
    /// </summary>
    internal override DictionaryMeta Meta
    {
      get { return Keys.Meta; }
    }
  }
}
